Crystallization of liquids on a solid surface can be initiated by either heterogeneous nucleation or prefreezing. The latter phenomenon is the crystalline layer formation at an interface to a solid substrate at a temperature higher than that of a bulk crystal. As it was recently determined, prefreezing is a first-order transition, since the formation of the crystalline phase is abrupt and reversible.

Here, we present a phenomenological theory of prefreezing and analyze such equilibrium properties as the temperature dependent thickness of the prefrozen layer, the maximum temperature range of prefreezing Tmax, and the mesoscopic jump of thickness during crystallization or melting. The theory provides a clear first-principles explanation of the first-order nature of prefreezing and defines the corresponding transition temperature Tmax as a function of the interfacial free energies. As shown, it is the difference of the interfacial energies that controls Tmax and serves as a driving force for prefreezing. The theoretical outcomes are applied to quantify the recent experimental results for poly(є-caprolactone) crystallized on graphite via prefreezing.